Thin-walled members such as blisks, aeroengine blades, turbine blades are key functional structural parts of airplanes, vessels and so on, and the level of machining of these parts directly determines the development of industries such as aerospace and navigation. In one aspect, these thin-walled members have complex curved surfaces, and are hard to be machined automatically; in another aspect, high requirements are imposed on the machining precision and surface quality of key parts such as blisks, and the surface quality issues such as surface burning and surface defects should be avoided, and in addition, the machining efficiency should also be guaranteed.
The thin-walled members such as blisks are mainly made of high-strength, heat-resistant and corrosion-resistant materials such as titanium alloy and nickel-based alloy, and pertain to typical complex structural parts having an integrally thin-walled structure and being hard to machine. Generally, these thin-walled members are first roughly machined to be shaped by five-shaft numerical control milling and linear friction welding or the like, and then are grinded and polished. Currently, manual grinding is mainly employed in engineering practice, and this way has a low efficiency, and has lots of issues such as a high rejection rate, a poor product consistency, and a low economy benefit, which seriously restricts the large area promotion and application of blisks in the aerospace field.
Abrasive belt grinding uses an abrasive belt as a grinding tool to machine the surface of a workpiece, and belongs to a flexible grinding, and can obtain a higher material removing rate and a better surface quality compared with grinding with a grinding wheel. In addition, the significant advantages of the abrasive belt grinding are as follows, it has higher grinding flexibility and adaptability, and can realize the grinding of planes, holes and grooves, and complex curved surfaces by changing the dimension of a contact wheel. The complex structural parts such as blisks cannot be machined by a grinding machine tool using the grinding wheel, and must be grinded by an abrasive belt grinding head with a small-diameter contact wheel. Zhi GENG et al. in Zhengzhou Research Institute for Abrasive & Grinding made experimental researches on the principle of abrasive belt grinding, and studied the effects of a contact wheel, an abrasive belt, and grinding parameters on material removal and surface generation, thus providing a theoretical support for the abrasive belt grinding.
In recent years, automatic abrasive belt grinding machine tools have been developed rapidly. Huazhen ZHONG et al. in Huazhong University of Science and Technology made research on numerical control abrasive belt grinding of steam turbine blades. Multi-shaft linkage numerical control machine tools and corresponding numerical control system have been well developed, for example, numerical control lathes, numerical control milling machines, and numerical control machining centers, however, the research on multi-shaft numerical control grinding machines relatively lags behind, the key point is that an abrasive belt grinding and polishing device is required to not only realize the adjustment of a grinding force, but also realize control of the linear speed, winding and unwinding of the abrasive belt. In engineering, grinding and polishing heads fully meeting these requirements have not been applied in China, which significantly restricts the promotion, application and development of the multi-shaft numerical control grinding machines.